<?php
/**
 * 数据库连接，单例模式.
 */
class Db
{
    private static $_instance;
    private static $_connectSource;
    private $_dbConfig = array(
        'host' => '127.0.0.1',
        'user' => 'root',
        'password' => 'chen',
        'dbname' => 'sfkbbs',
    );

    private function ___construct()
    {
    }

    public static function getInstance()
    {
        if (!(self::$_instance instanceof self)) {
            self::$_instance = new self();
        }

        return self::$_instance;
    }

    public function connect()
    {
        if (!self::$_connectSource) {
            self::$_connectSource = mysql_connect($this->_dbConfig['host'], $this->_dbConfig['user'], $this->_dbConfig['password']);

            if (!self::$_connectSource) {
                throw new Exception('mysql connect error'.mysql_error());
            }

            mysql_select_db($this->_dbConfig['dbname'], self::$_connectSource);
            mysql_query('set names UTF8', self::$_connectSource);
        }

        return self::$_connectSource;
    }
}
